Touch screens have increasingly replaced the traditional keyboards, and the development of touch detection technologies have become relatively more mature. In existing designs with respect to touch detection of a capacitive touch screen, a scanning control unit of the capacitive touch screen controls each of drive lines Tx to sequentially send a driving signal along the scanning direction shown in FIG. 1A, and controls each of sense lines Ry to receive the signal synchronously, so that the position of a touch point is detected by comparing the capacitance before the touch with that after the touch, to obtain coordinates of the touch point. To prevent mal-operation and improve the detection accuracy of a touch point, generally pattern designs ensure that no less than 4 coordinate points would be touched by a finger every time, as shown in FIG. 1B, and then the relatively precise coordinates of the touch point are obtained by calculating the center or the gravity center of the no less than 4 coordinate points.
However, for a precise positioning, each of the drive lines Tx is scanned from the first drive line to the last drive line within each frame, to detect as many touch points as possible. However, such row-by-row scanning technique not only consumes more power, but also requires a large number of lines Tx and sense lines Ry that may exceed the capability of an integrated circuit for driving a large-sized screen. Further, in order to achieve a balance between driving capability and driving signal quality, the number of the drive lines Tx and the sense lines Ry is generally reduced. The reduced number of drive and sense lines, however, results in a reduced detection accuracy of a touch panel.